What happened
On September 10, 2013, an Embraer E170-100 was descending for approach at Gdańsk Airport (EPGD) when the crew received a "FLAPS LO RATE" message on the EICAS, followed by a "FLAPS FAIL" indication during flap extension. The crew performed a landing on runway 29 with flaps set to position 0 and slots 3. Due to the malfunction, the crew requested fire service assistance for the landing, though the aircraft arrived without further incident.
Following the initial landing, the aircraft was handed over to maintenance, which performed troubleshooting and operational tests. The tests were successful, and the aircraft was cleared for flight. However, the flap issue recurred during the aircraft's next flight on the same day. While climbing through FL 150 after departing from Gdańsk, the crew observed both a "FLAP LO RATE" alert and an "ADS 1 HTR FAIL" indication. The crew subsequently decided to divert the flight to Warsaw (WAW).
The investigation
The investigation focused on the repeated flap malfunctions and the secondary sensor alert. After the second landing in Warsaw, maintenance personnel performed mechanical and electrical rigging of the flap system according to the Aircraft Maintenance Manual (AMM). While the flap system functioned correctly following these adjustments, the "ADS HTR FAIL" alert could not be replicated during ground testing but reappeared during a subsequent technical test flight.
Findings
- The primary cause of the flight incidents was the spontaneous misalignment of the flap system.
- Maintenance actions included the mechanical and electrical rigging of the flap system.
- To resolve the recurring ADS alert, the Air Data Smart Probe No. 2 was replaced.